We went on a whale watching trip a few years ago. Scientists are able to track each whale through their tail fins, which have a unique pattern. Through photographs taken at the turn of the century they had identified whales that were still swimming the same waters over a century later - in other words, whales that were swimming the ocean before WW I, before the Russian Revolution, before the WW II and the atomic bomb, etc. - were still alive, having lived through all that human history. I found it to be very moving ... really a privilege to spend a few hours with these magnificent mammals. Thanks for this!